The increased use of microwaves for cooking has given rise to a large market in microwavable foods. While the advantage of microwave cooking over convection oven cooking is the time savings, the disadvantage heretofore has been that flavored baked goods do not develop the surface flavoring (in addition to browning or crust formation) or internal flavoring expected with convection oven cooking.
Our objective has been to create that internal and/or surface flavor retention and, optionally, browning which enhances the products' appearance, taste and mouth feel properties making it look as if it were cooked in a convection oven and making it taste as if it were cooked in a convection oven; particularly applied to chocolate flavored foodstuffs.
Heretofore, when using the microwave oven for cooking foodstuffs containing flavoring and browning formation additives, the food to be cooked taken in combination with additives therefor did not have the proper time-temperature-heat transfer variable (e.g., heat capacity, thermal conductivity, viscosity and density) combination for the (i) added materials useful for surface and/or internal flavoring to be effective or (ii) added chemicals responsible for browning and/or crust formation to react. Therefore, for a microwave (i) internal or surface flavoring system to work and (ii) browning and/or crust system to work, firstly, it must excellerate the rate of the browning reactions or locally increase the surface temperature and, secondly, the physical heat and mass transfer conditions must be such that the added flavor values; internal and/or surface must not be driven off or destroyed.
Ultimately, the reactions responsible for browning and/or flavor formation, particularly chocolate flavor formation have to be accomplished in the relatively short time frame dictated by the foods' preparation conditions. The times needed for preparing microwave foods vary depending upon the power output of the microwave unit and the mass of the food to be cooked. A typical 750 watt microwave will cook baked goods in 40 seconds to 4 minutes.
Several additional requirements for a successful microwave flavor retention system are as follows:
1. formation of a flavor (e.g., chocolate flavor) having authentic aroma and taste nuances; PA1 2. retention of authentic flavor (e.g., chocolate) aroma and taste nuances. PA1 1. in addition to the desired browning effect, it must generate either no aroma or one which is compatible with the target food (e.g., a chocolate flavored food such as a "brownie"); PA1 2. the browning reaction must not take place before cooking the food; and PA1 3. after cooking, the browning must stop, and not cause the food to be darkened substantially so that it becomes aesthetically displeasing.
Furthermore, when appropriate, several additional requirements for a successful microwave browning system are as follows:
The reaction responsible for chocolate flavor formation during convection oven cooking is the reaction between sugar, leucine and phenyl alanine which results in the creation of various reaction products including aldol condensation products such as COCAL.RTM. (a Registered Trademark of International Flavors & Fragrances Inc.) having the structure: ##STR1##
Furthermore, the reactions responsible for browning during convection oven cooking are the carmelization of sugars and the Maillard reaction between naturally occurring reducing sugars, amino acids, amines, peptides and proteins which results in the formation of colored melanoidins. Until recently (1984) there were numerous patent and literature references to such reactions for the production of flavors, where the generation of color was inconsequential or objectionable. In the past few years several patents have appeared wherein microwave browning created by Maillard reactions have been the topic.
Although the prior art does take advantage of the reaction between reducing sugars and amino acids, it has not made any correlation of reaction rates needed for browning reactions with reaction variables such as pH, solvent, amino acid reactivity or sugar reactivity.
Furthermore, although the prior art takes advantage of the reaction between amino acids and sugars to form flavors, e.g., chocolate flavors again it has not made any correlation of reaction rates needed for flavor retention with reaction variables such as pH, solvent, amino acid reactivity or sugar reactivity.